Congenital pulmonary venolobar syndrome with pseudo-horseshoe lung

Clinical History

A 8-month-old male infant was transfered to our hospital for cardiology consultation because of cardiac dextroposition, acute cough and polypnoea. On physical examination, cyanopathy and pallor were observed, a grade 3 systolic ejection murmur over the left second-to-fourth intercostals space and a little lung rale were heard.

Imaging Findings

The echocardiogram found dextroposition of the heart, atrial septal defect and pulmonary hypertension. Chest computed tomography showed dextroposition of the heart, dysplasia of the right lung and herniation of the right pulmonary lobe located in the left hemithorax which was pseudohorseshoe lung (Fig. 1). Multidetector computed tomographic angiography demonstrated the smaller right pulmonary vessels (dysplasia of the right lung), the right pulmonary veins totally draining to the mouth of the inferior veno cava (total anomalous pulmonary venous drainage), dilated azygos veins and atrium septal defect (Fig. 2). What is more, trachea trifurcation was found by 2/3 dimensional minimum intensity projection, volume rendering reconstruction and virtual endoscopy (Fig. 3).

Discussion

Congenital pulmonary venolobar syndrome is a group of congenital malformations of the thorax. Major components are hypogenetic lung, partial anomalous pulmonary venous return, pulmonary sequestration, absence of the pulmonary artery, systemic arterialisation of the lung without sequestration, absence or interruption of the inferior vena cava and duplication of the diaphragm [1]. Hypogenetic lung and partial anomalous pulmonary venous return (PAPVR) are the most common of this group, both of which come together in rare cases. Hypogenetic lung may occur not only on the right side, but also in the left pulmonary Lobe [2-4]. Right pulmonary hypoplasia could explain dextroposition of the heart and the mediastinum shift. PAPVR is always termed scimitar syndrome, that is, the anomalous pulmonary venous return of all or most of the right lung to the inferior vena cava just below or above the right hemi-diaphragm creates the image of a Turkish sword on the chest X-radiography [5]. Scimitar syndrome is usually accompanied by horseshoe lung, which is the partial fusion of the right and left pulmonary lobes with the absence of an isthmus in the midline. Nonexistence of the pleural membrane is a true horseshoe lung malformation [1, 6]. In our case, the right pulmonary lobe just crossed the thorax with a basal segment herniation, there was a pleural fissure dividing the left and right lung, which was so-called pseudohorseshoe lung. Besides, tracheal trifurcation was detected by multidector computed tomography, which is one of minor components of CPVLS including tracheal trifurcation, eventration and partial absence of the diaphragm, phrenic cyst, horseshoe lung, oesophageal and gastric lung, anomalous superior vena cava, and absence of the pericardium [1, 7, 8]. Traditionally, thoracic developmental anomalies are detected by X-radiography and usually completed by echocardiogram. Cardiac catheterisation could be used for confirming diagnosis and even for interventional therapy in some circumstances. Development of imaging techniques such as computed tomography and magnetic resonance imaging make a detailed diagnosis more possible. As the patient described in our case report, diagnosis of congenital pulmonary venolobar syndrome was easily established, because of detection of hypogenetic lung, partial anomalous pulmonary venous return, pseudohorseshoe lung and tracheal trifurcation, and some other combined abnormalities could be found, such as dilated azygos veins, atrium septal defect and pulmonary hypertension. Many important records were measured noninvasively to estimate general conditions of the patient before surgery, such as the size of the hypogenetic pulmonary artery, volumes of the heart chambers and details of the left-to-right shunt.